New Defense Sent In To Stop Colds' Offensive Attack

Scientists Tackle Immune System

One might think that with so many intelligent doctors and so much high-tech medical research around, someone could cure a measly cold.

No one has, and according to experts, no one will soon, although drug companies gross $2 billion a year peddling remedies for sniffles, sore throats and similar respiratory malaises.

Yet, there may be reason for hope.

Rather than abandoning cold sufferers to their self-limited miseries, some researchers are plotting a new plan of attack, one that will help unlock one of the body's great mysteries: the immune defense system.

Smart scientists have given up trying to kill viral parasites. Instead, they want to biochemically squelch the signs of the battlefield-the chills, coughs and aching joints-before they occur.

"If you get infected with a (cold) virus, it triggers a response that makes you sick," said Dr. Ronald Turner, an infectious disease specialist at the Medical University of South Carolina, Charleston.

To thwart a cold, reasoned Turner and colleagues, people might be able to modify the body's immune response before it becomes overzealous in what he calls "a side-reaction" to the virus.

The key is to find the exact immunochemical trigger of cold symptoms, then conjure up methods to block or dampen it. That way, the body could still fight the virus, but avoid two weeks of aching annoyance.

Some experts such as Dr. Gary Noskin, an infectious disease specialist at Northwestern University, agree that some researchers are shifting their viral-attack strategy, in general.

Where previously the focus was viruses, now it is immunity. Scores of experiments are under way involving all aspects of the cells that affect the immune system, devising ways to shut them off, supercharge them or alter their genes. Scientists, however, disagree whether this is the best approach.

Most of the research involves such killers and cripplers as cancer, AIDS and rheumatoid arthritis, but there is a stalwart band studying the common cold.

"It is virtually impossible to prevent the common cold," Noskin said. "But if this preliminary work is accurate, we might be able to block the symptoms."

Some researchers are skeptical about shutting down the immune system, but most agree that the only hope for conquering viruses will come from a better understanding of the body's natural immune processes.

That way, colds symptoms would vanish forever. And with them, the huge market for over-the-counter nostrums that do little more than relieve discomfort.

The reason that such drugs don't cure colds is because colds are caused by at least 100 different viruses, tiny parasites made of a single DNA strand surrounded by a protective outer shell.

Such viruses can quickly change both their DNA inside the shell and the signals on their outside capsule in order to fool the immune system. Evolution has provided them with clever ways to survive and thrive, at least for a while.

Rhinoviruses, adenoviruses and paraviruses-each differs according to its genetic material and outside coat-but all have eluded development of effective vaccines or antiviral drugs.

The adenovirus is shaped like a very tiny 20-sided soccer ball. Sticky outgrowths called fiber allow it to cling to cell surfaces like burrs to animal fur. Once a respiratory tract cell senses that a virus has latched on, it quickly swallows the parasite.

That is exactly what the virus hopes for. Then, the tiny invader can seize the cell's reproductive machinery and begin churning out countless copies of itself. The result: a miniature virus factory.

Meanwhile, the human body spreads the virus far and wide via moisture-laden saliva droplets, sneezed into the air or passed on by contaminated hands.

Tissues, drinking glasses and even doorknobs can be sources of invisible predators, since the robust viruses can live for days outside the body.

According to the Center for Health Statistics, an estimated 1 billion colds occurred in the U.S. in 1992. This translated to 157 million days of restricted activity and 15 million days of lost work.

Children, on average, get roughly six to eight colds each year. Adults average two to four per year.

Nevertheless, experts caution that the risks of treatments have to be weighed against the seriousness of the illness, particularly when researchers would dare to tamper with the body's natural immunity.

"We're not talking about a cure for cancer," Noskin said. "A cold will cure itself."

It seems likely that scarce research dollars will be channeled into treating viral-induced diseases such as herpes and AIDS that are not self-limiting and have more serious consequences.

Nevertheless, a growing group of colds researchers are pursuing a new high-tech approach. They hope to pinpoint specific immunochemical triggers for attack, while leaving the rest of the body's defenses untouched.